andrew@webrtc.org | a7b57da | 2012-10-22 18:19:23 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license |
| 5 | * that can be found in the LICENSE file in the root of the source |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | |
| 11 | |
| 12 | /* |
| 13 | * This file contains the function WebRtcSpl_SqrtOfOneMinusXSquared(). |
| 14 | * The description header can be found in signal_processing_library.h |
| 15 | * |
| 16 | */ |
| 17 | |
pbos@webrtc.org | abf0cd8 | 2013-05-27 09:49:58 +0000 | [diff] [blame] | 18 | #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h" |
andrew@webrtc.org | a7b57da | 2012-10-22 18:19:23 +0000 | [diff] [blame] | 19 | |
pbos@webrtc.org | 1727dc7 | 2013-04-09 16:40:28 +0000 | [diff] [blame] | 20 | void WebRtcSpl_SqrtOfOneMinusXSquared(int16_t *xQ15, int vector_length, |
| 21 | int16_t *yQ15) |
andrew@webrtc.org | a7b57da | 2012-10-22 18:19:23 +0000 | [diff] [blame] | 22 | { |
pbos@webrtc.org | 1727dc7 | 2013-04-09 16:40:28 +0000 | [diff] [blame] | 23 | int32_t sq; |
andrew@webrtc.org | a7b57da | 2012-10-22 18:19:23 +0000 | [diff] [blame] | 24 | int m; |
pbos@webrtc.org | 1727dc7 | 2013-04-09 16:40:28 +0000 | [diff] [blame] | 25 | int16_t tmp; |
andrew@webrtc.org | a7b57da | 2012-10-22 18:19:23 +0000 | [diff] [blame] | 26 | |
| 27 | for (m = 0; m < vector_length; m++) |
| 28 | { |
| 29 | tmp = xQ15[m]; |
| 30 | sq = WEBRTC_SPL_MUL_16_16(tmp, tmp); // x^2 in Q30 |
| 31 | sq = 1073741823 - sq; // 1-x^2, where 1 ~= 0.99999999906 is 1073741823 in Q30 |
| 32 | sq = WebRtcSpl_Sqrt(sq); // sqrt(1-x^2) in Q15 |
pbos@webrtc.org | 1727dc7 | 2013-04-09 16:40:28 +0000 | [diff] [blame] | 33 | yQ15[m] = (int16_t)sq; |
andrew@webrtc.org | a7b57da | 2012-10-22 18:19:23 +0000 | [diff] [blame] | 34 | } |
| 35 | } |